Bounce suppressing mechanism

ABSTRACT

A spring having one end slidably engaging a pin extending from a retractable, motion inducing member, for example a print hammer in a printing apparatus, is rotatably mounted adjacent to a movable member, such as a type wheel. An intermediate portion of the spring is formed to contact and bear against the shaft of the type wheel so that when the print hammer is retracted, the spring is rotated about its mounting. This rotation results in the intermediate portion of the spring biasing the type wheel toward the print hammer. When the print hammer is brought into striking engagement with the type wheel, the pin on the print hammer moves thereby reducing the biasing action of the spring on the type wheel. Thus, the type wheel is free to move after being struck by the print hammer, but subsequent retraction of the print hammer applies a bias through the spring to suppress bouncing motion of the type wheel.

United States Patent 1191 -lung [4 A r. 30, 1974 BOUNCE SUPPRESSINGMECHANISM [75] Inventor: Werner Jung, Morton Grove, Ill. [57] ABSTRACT[73] Assignee: Teletype Corporation Skokie, A spring having one endslidably engaging a pin ex- [22] Filed; Aug 21, 7 tending from aretractable, motion inducing member, for example a print hammer in aprinting apparatus, is PP 282,090 rotatably mounted adjacent to amovable member, such as a type wheel. An intermediate portion of the 52US. Cl. 197/55, 101/93 c Spring is formed to Contact and bear againstthe Shaft [51] Int. Cl. G4lj 27/00 of the type Wheel so that when thePrint hammer is 58] Field of Search 197/18, 52, 53, 55, 17; "acted, theSpring is rotated about its mounting This 101/93 176/36 rotation resultsin the intermediate portion of the spring biasing the type wheel towardthe print ham- [56 References Cited mer. When the print hammer isbrought into striking UNITED STATES PATENTS engagement with the typewheel, the pin on the print 7 1967 H I 101 93 C X hammer moves therebyreduclng the biasmg actlon of 322133 111965$32531:::::::::::::::::::::.... 181,93 C Spring on the e wheel- The theh Wheel 18 3,504,623 4/1970 Sjallerm" 101/93 c we to move after l Struckby.the F 3,139,820 7/1964 Kittler 101/93 c but Subsequent rgtrachoh ofthe Pm1t hammer aPPes Primary ExaminerRobert E. Pulfrey AssistantExaminerR. T. Rader Attorney, Agent, or Firm-J. L. Landis a bias throughthe spring to suppress bouncing motion of the type whe'el.

5 Claims, 4 Drawing Figures BOUNCE SUPPRESSING MECHANISM BACKGROUND OFTHE INVENTION 1. Field of the Invention This invention relates to abounce suppressing mechanism for a movable member, and particularlyrelates to a mechanism for minimizing the rebound of a type wheel in aprinting apparatus after each printing operation.

2. Discussion of the Prior Art In various forms of printing apparatus, amovable type carrier is struck by a print hammer driving the typecarrier toward a print receiving medium supported and backed by aplaten. After the type carrier has contacted the platen, the typecarrier rebounds from the platen and strikes either the print hammer orits backstop. If the type carrier is of sufficient mass, the typecarrier will also rebound from the print hammer and will again contactthe platen. This bouncing action of the type carrier causes smudging orblurring of the print receiving medium.

For example, US. Pat. No. 3,176,068 issued to N. A. Jacobs illustratesand describes a type wheel actuator mechanism including a cylindricaltype wheel having type characters arranged on four levels. The typewheel is selectively positioned and then driven by the impact of a printbail or hammer toward the platen to perform a printing operation. Alight coil spring bears against the shaft of the type wheel to insurerestoration of the type wheel to a substantially vertical position aftereach printing operation.

It is desirable to increase the number and variety of type charactersavailable on the type wheel. Increasing the number of type characterswithout reducing their size necessarily results in a larger, moremassive type wheel. Then, however, the more massive type wheel issusceptible to bouncing action of increased magnitude after being struckby the print hammer. The light coil spring used with the less massivetype wheel, such as the type wheel shown in the Jacobs patent, is notcapable of suppressing the bouncing motion of the heavier type wheel.Thus, substantial smudging of the print receiving mechanism occurs whenthe larger type wheel is used.

Advantageously, the type wheel should be free to move toward the platento effect a printing operation immediately after being struck by theprint hammer, but the type wheel should not be free to rebound towardthe platen at other times. Various forms of shock absorbing andcushioning devices for minimizing the rebound of moving members, such astype wheels, are known in the prior art. Generally, these devices merelyapply a continuous anti-rebound force to the member, contrasted topermitting the member to move freely in the desired direction whenstruck by a motion inducing member and suppressing only the bouncingaction.

Other devices for minimizing bounce may be coupled to a motion inducingmember, such as a print hammer, and are totally ineffective for reducingthe bounce or rebound of the moving member, such as a type wheel.

SUMMARY OF THE INVENTION It is, therefore, an objective of thisinvention to provide a new and improved bounce suppressing mechanism fora movable member.

Another object of this invention is to provide a new and improvedmechanism for'minimizing the rebound of a type wheel in a printingapparatus.

A further object of this invention is to provide a new and improvedmechanism for suppressing the bounce of a movable member whenever anassociated'motion inducing member is in a nonmotion inducing position.

A bounce suppressing device in accordance with the principles of theinvention may be included in a mechanism having a first member movablein-a forward direction and a retracting direction and a second memberwhich is movable upon application of a striking force thereto. Apreferred embodiment of the bounce suppressing device may couple thefirst and second members to permit the second member to move freely uponapplication of the striking force as long as the first member is movingin a forward direction. Upon movement of the first member in aretracting direction, however, the bounce suppressing device applies abiasing force to the movable second member to preclude undesirablebounce of the second member after application of the striking force.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of thepresent invention will be apparent from the following detaileddescription when considered in conjunction with the accompanying drawingin which:

FIG. 1 is a partial end elevational view of a printing apparatus withparts broken away to illustrate a bounce suppressing mechanism inaccordance with the principles of this invention; 7

FIG. 2 is a view, partly in plan and partly in section, taken along theline 2-2 of FIG. 1, of the bounce suppressing mechanism;

FIG. 3 is a fragmentary end view of the printing apparatus of FIG. 1showing a print hammer in one position as it advances toward a typewheel; and

FIG. 4 is a view of the print hammer and the type wheel of FIG. 3 in theposition of contact between the struck the type wheel.

DETAILED DESCRIPTION Referring to FIG 1 there is illustrated a printingapparatus, designated generally by the numeral 11, with parts brokenaway to show a bounce suppressing mechanism, designated generally by thenumeral 12, in accordance with the principles of this invention.

The printing apparatus 11 is similar to the telegraphic page printerillustrated in the aforementioned Jacobs patent, the disclosure of whichis incorporated herein by reference insofar as may be necessary tounderstand the structure and operation of the type of mechanismdescribed and claimed herein.

The printing apparatus 11 includes a casting 13 which is movabletransversely of a platen 14 and which carries a retractable print hammer16 and a type wheel 17. A marking ribbon l8 and a print receiving medium19, such as a web of paper,.are interposed between the type wheel 17 andthe platen 14. The type wheel 17 may be selectively positioned relativeto the platen 14 to orient a selected type character (not shown) carriedon the type wheel. The print hammer 16 may then be operated to engageand move the type wheel 17 toward the platen 14 so that the selectedtype character presses the marking ribbon 18 into printing engagementwith theprint receiving medium 19. Subsequent retraction of the printhammer 16 c ompletes one printing operation.

In the aforementionedpatent of N. A. Jacobs there is described in detaila mechanism 'for controlling the rotational and reciprocal motion of thetype wheel 17. The type wheel 17 is cylindrical and has type characterson the outer surface which may be arranged-in a plurality of levels suchas, for example, six levels. The type wheel 17 is mounted on a shaft 21which is pivotally mounted at one end (not shown) to permit pivotalmovement of the type wheel toward the platen 14 (FIG. 4). The shaft 21is also fixed to a bearing ring (not shown) which is mounted forrotation and carries an annular gear 22 (FIG. 2).

A pair of racks 23 and 24 (FIG. 2) are slidably mounted on a spacerplate 26 and are supported and guided by a pair of shouldered buttons 27and 28 (FIG. 2) which are mounted on a support plate 29. The pair ofracks 23 and 24 engage the annular gear 22 to selectively rotate thetype wheel 17.

Another mechanism (not shown), but described in detail in theaforementioned patent of N. A. Jacobs, provides selective reciprocalmotion to the shaft 21 and the type wheel 17, so that the combination ofreciprocal and rotary motion can bring any type character on the typewheel into printing orientation.

Referring now to FIG. 2 there is illustrated, partly in plan and partlyin section taken along the line 22 of FIG. 1, a view of the'printingapparatus 11. The print hammer 16 is oscillatably mounted on a shaft 32which is in turn supported on a pair of side plates 33 and 34 extendingupwardly from the support plate 29. A coil spring 36, having a first end37in engagement with a portion of the side plate 34, encircles the shaft32. A second end 38 of the coil spring 36 is bent at a right angle sothat the second end bears against one side of the print hammer 16 tourge the print hammer in a clockwise direction as viewed in FIG. 1.

Referring again to FIG. 1, the print hammer 16 is retracted, into theposition shown, against'the force of the coil spring 36 (FIG. 2) by aprint hammer actuating link 39, the upper end of which has a hookportion 41 that engages a hub 42 extending from the side of the printhammer.

A mechanism (not shown) is provided to move the print hammer actuatinglink 39 upwardly to release its control over the print hammer 16. Theprint hammer 16, however, will be held in the retracted position by alatch 44 having a latching portion 46 in engagement with a latchingshoulder 47 formed in the print hammer. A print suppress latch 48 isalso provided to engage the latching shoulder 47 when the printingapparatus 11 receives a signal which does not require a printingoperation, for example, a space or a line feeding function.

The second end portion 38 (FIG. 2) of the coil spring 36 (FIG. 2) islimited in travel by the side plate 33 which is formed to engage thesecond end portion when the print hammer 16 is released by both thelatching portion 46 and the print suppress latch 48. When the printhammer 16 is released, it is driven toward the type wheel 17 by theaction of the coil spring 36 (FIG. 2). The second end portion 38 willstrike the side plate 33 permitting the print hammer 16 to continuemoving toward type wheel 17 on its own momentum.

Also mounted on the support plate 29 is a mechanism for lowering themarking ribbon 18 out of the printing position so that the typecharacters previously printed may be observed. A shaft 51 is rotatablymounted on the support plate 29 and has a trip and restoring lever 52fixed to one end and a restoring lever 53 (FIG. 2) fixed to the otherend. The trip and restoring lever 52 is coupled to a link 54 whichcontrols the rotation of the shaft 51. Rotation of the shaft 51 raisesor lowers the marking ribbon 18, which is held in a ribbon guide (notshown), into and out of printing position, respectively.

The printing. apparatus 11 and its operation, as described above, areillustrated and described in further detail in the aforementioned patentof N. A. Jacobs.

The bounce suppressing mechanism 12 includes a spring 56 having a firstend 57 which slidably engages a pin 58 extending from the hub 42 of theprint hammer 16 and a second end 59 (FIG. 2) disposed generallyperpendicular to the first end and rotatably mounted in a first pivot orsleeve 61 (FIG. 2) which is secured to the support plate 29.

The first pivot 61 is mounted on the support plate 29 between the typewheel 17 and the platen 14 so that the shaft 21 of the type wheel islocated between the print hammer 16 and the first pivot.

Referring again to FIG. 2, the spring 56 furtherhas an intermediatesection 62 formed into a loop portion 63. The loop portion 63 is locatedbetween the first pivot 61 and a second pivot or sleeve 64, which isalso mounted on the support plate 29. The first and second pivots 61 and64 position the loop portion 63 so thatit bears against shaft 21 of thetype wheel 17.

It will be apparent that the loop portion 63 may be of any convenientshape or may include an additional element extending fromtheintermediate portion 62 of the spring 56 to contact and bear against theshaft 21.

When the print hammer 16 is in the position shown in FIG. 1, the pin 58holds the first end 57 of the spring 56 in the retracted position aboutthe pivots 61 and 64 so that the type wheel 17 is retracted or biasedaway from the platen 14 by the force of the spring.

A mounting plate 67 is spaced above and secured to the support plate 29intermediate the print hammer 16 and the annular gear 22, by a pair ofscrews 68 and 69. A pair of rocker members 71 and 72 are pivotablymounted between the mounting plate 67 and the support plate 29 by thepair of screws 68 and 69, respectively.

Each of the pairof rocker members 71 and 72 is formed with an upwardlyextending projection 73 and 74, respectively, which support a coilspring 76 stretched between them.

The coil spring 76 stretched between the pair of'projections 73 and 74exerts a biasing force on the rocker members 71 and 72 which pivots therocker members about the screws 68 and 69, respectively. This pivotalmotion of the rocker members 71 and 72 rotates them into contact withthe racks 23 and 24.

The force applied to the racks 23 and 24 through the rocker members 71and 72 urges the racks into firm engagement with the annular gear 22.This firm engagement substantially eliminates play or backlash betweenthe annular gear 22 and the gear teeth carried on the racks 23 and '24.i

In operation, to initiate a printing operation, the print hammer 16 isreleased by a mechanism (not shown) from the retracted position shown inFIG. 1 by the latch 44 and the print suppress latch 48 and is rotatedabout the shaft 32 by the coil spring 36, driving the print hammertoward the type wheel 17. The second end portion 38 of the coil spring36 then engages the side plate 33 thereby stopping the rotation of thecoil spring but permitting the print hammer 16 to continue, on its ownmomentum, rotating about the shaft 32.

Referring now to FIG. 3 there is illustrated a fragmentary view of theprinting apparatus 11 and the bounce suppressing mechanism 12 of FIG. 1,showing the print hammer 17 in one position as it advances toward theplaten 14.

Comparing the relative positions of the shaft 32 and the pin 58 in FIG.1 and in FIG. 3, it will be apparent that the pin is displaced in aclockwise direction around the shaft as the print hammer 16 rotatesabout the shaft and advances toward the type wheel 17. In the positionshown in FIG. 1, the pin 58 holds the first end 57 of the spring 56 inthe retracted position so that the loop portion 63 bears against theshaft 21 of the type wheel 17. The biasing force applied to the shaft 21by the loop portion 63 in turn urges the first end 57 in an upwarddirection so that a biasing force is also applied to the pin 58 by thefirst end. Thus, clockwise displacement of the pin 58 permits the firstend 57 of the spring 56 to slide along the pin moving the first endupwardly as shown in FlG. 3.

As the first end 57 moves upwardly, the retracting or biasing forceexerted on the shaft 21 of the type wheel 17 by the loop portion 63 ofthe spring 56 is reduced, permitting the type wheel to move freelytoward the platen 14 after being struck by the print hammer 16.

Referring now to F IG. 4 there is shown the type wheel 17 in theprinting position contacting the platen 14 after being struck by theprint hammer 16. After the biasing force exerted on the shaft 21 hasbeen removed by the upward movement of the pin 58 as shown in FIG. 3,the print hammer l6 continues to rotate about the shaft 32 until theprint hammer strikes the type wheel 17. The type wheel 17, having beenpreviously positioned so that a selected type character carried thereonis in printing orientation, is driven toward the platen 14 by the impactof the print hammer 16. When the type wheel 17 contacts the platen 14,the marking ribbon 18 is forced into engagement with the print receivingmedium 19, which is supported by the platen 14, to print the selectedtype character. The motion of the type wheel 17 between the time it isinitially struck by the print hammer 16 and the time the type wheelfirst strikes the platen 14 occurs with minimum restraint from thebounce suppressing mechanism 12.

The print operation is completed by retracting the print hammer from theposition shown in FIG. 4 toward the position shown in FIG. 1, with thehook portion 41 of the actuating link 39 engaging the hub 42 whichextends from the print hammer.

Retraction of the print hammer 16 moves the pin 58 in a counterclockwisedirection about the shaft 32, or downwardly as viewed in FIG. 4. Thiscounterclockwise movement of the pin 58 also moves the first end 57 ofthe spring 56 downward, applying an increasing force to the shaft 21through the loop portion 63 to bias the type wheel'l7 away from theplaten 14. As the pin 58 continues to move toward the positionof FIG. l,the

bias force applied to the shaft 21 rapidly increases.

After the type wheel 17 has initially struck the platen 14, the typewheel rebounds from the platen toward the print hammer 16 as it is beingretracted. Although the type wheel 17 is free to rebound from the platen14, any further rebound or bounce such as rebound from contact with theprint hammer 16 as it is retracted, will be restrained by the bouncesuppressing biasing force of the spring 56.

Thus bounce of the type wheel 17 is minimized by the bounce suppressingmechanism 12 whenever the print hammer 16 is in a retracted position, oris being retracted. The type wheel 17 is permitted to move freely towardthe platen 14 only when initially struck by the print hammer 16 duringeach printing operation and is not free to rebound toward the platen atother times. In this way, the type wheel 17 strikes the platen 14 onlyonce during each printing operation, thereby preventing smudging orblurring of the type characters printed on the print receiving medium19.

It is to be understood that the above-described embodiment is simplyillustrative of the invention, other embodiments may be devised by thoseskilled in the art which will employ the principles of the invention andface, a mechanism for suppressing the bounce of the v movable memberafter striking the surface, which comprises:

a pivot mounted adjacent to the movable member;

a pin extending from the retractable hammer; and

means responsive to retraction of the hammer, for

releasably applying a biasing force to the movable member to bias themovable member away from the surface and toward the retractable hammer,said means having a first end portion for engaging said pin and a secondend portion mounted in said pivot for movement relative thereto so thatupon retraction of the hammer said pin engages said first end portion toreleasably apply said biasing force to a third portion intermediate saidfirst and second end portions, said third portion being formed tocontact and bear against the movable member so that said biasing forceis applied thereby whenever the hammer is retracted and so that uponinitial movement of the hammer toward the movable member said pinrelieves said biasing force thereby permitting the movable member tostrike the surface.

2. In a printing apparatus having a retractable hammer, a movable typewheel, and a printing medium, a mechanism for suppressing the bounce ofthe type wheel after each printing operation, which comprises:

a pin extending from a side portion of the retractable hammer; and

a spring having a first end slidably engageable with said pin, a secondend rotatably secured between the type wheel and the printing medium,and an intermediate portion formed to contact a portion of the typewheel so that said pin slidably engages and biases said first end uponretraction of the hammer to rotate said second end and thereby move saida distinct means, separate from the retractable hammer and the movablemember, coupling the retractable hammer and the movable member andresponsive to the retraction of the hammer, and applying a biasing forceto bias the movable member toward the retractable hammer;

I and means responsive to the initiation of movement of the retractablehammer into striking engagement' with the movable member for relievingsaid biasing force so that the movable member is freely movable whenstruck by the retractable hammer the distinct means having a firstportion cooperating with the relieving means and a second portionmounted for piovtal movement.

4. A mechanism as set forth in claim 3 wherein said distinct meanscomprises a spring having the first portion held in biasing engagementwith the relieving means and a third portion bearing upon the movablemember to exert a bounce suppressing biasing force thereon when thehammer is moved in the retracting direction. I

5. A mechanism as set forth in claim 4 wherein said relieving meanscomprises a pin extending from the hammer and slidably engaging saidfirst portion of said spring so that, upon movement of the hammer intostriking engagement with the movable member, said pin slides along saidfirst portion to relieve the biased engagement of the first portion withthe hammer thereby releasing the bounce suppressing biasing force fromapplication to the movable member.

1. In a device having a retractable hammer for driving a movable memberinto striking contact with a surface, a mechanism for suppressing thebounce of the movable member after striking the surface, whichcomprises: a pivot mounted adjacent to the movable member; a pinextending from the retractable hammer; and means responsive toretraction of the hammer, for releasably applying a biasing force to themovable member to bias the movable member away from the surface andtoward the retractable hammer, said means having a first end portion forengaging said pin and a second end portion mounted in said pivot formovement relative thereto so that upon retracTion of the hammer said pinengages said first end portion to releasably apply said biasing force toa third portion intermediate said first and second end portions, saidthird portion being formed to contact and bear against the movablemember so that said biasing force is applied thereby whenever the hammeris retracted and so that upon initial movement of the hammer toward themovable member said pin relieves said biasing force thereby permittingthe movable member to strike the surface.
 2. In a printing apparatushaving a retractable hammer, a movable type wheel, and a printingmedium, a mechanism for suppressing the bounce of the type wheel aftereach printing operation, which comprises: a pin extending from a sideportion of the retractable hammer; and a spring having a first endslidably engageable with said pin, a second end rotatably securedbetween the type wheel and the printing medium, and an intermediateportion formed to contact a portion of the type wheel so that said pinslidably engages and biases said first end upon retraction of the hammerto rotate said second end and thereby move said intermediate portion tourge the type wheel toward the retractable hammer.
 3. In a device havinga retractable hammer for striking a movable member, a mechanism forsuppressing the bounce of the movable member which comprises: a distinctmeans, separate from the retractable hammer and the movable member,coupling the retractable hammer and the movable member and responsive tothe retraction of the hammer, and applying a biasing force to bias themovable member toward the retractable hammer; and means responsive tothe initiation of movement of the retractable hammer into strikingengagement with the movable member for relieving said biasing force sothat the movable member is freely movable when struck by the retractablehammer the distinct means having a first portion cooperating with therelieving means and a second portion mounted for piovtal movement.
 4. Amechanism as set forth in claim 3 wherein said distinct means comprisesa spring having the first portion held in biasing engagement with therelieving means and a third portion bearing upon the movable member toexert a bounce suppressing biasing force thereon when the hammer ismoved in the retracting direction.
 5. A mechanism as set forth in claim4 wherein said relieving means comprises a pin extending from the hammerand slidably engaging said first portion of said spring so that, uponmovement of the hammer into striking engagement with the movable member,said pin slides along said first portion to relieve the biasedengagement of the first portion with the hammer thereby releasing thebounce suppressing biasing force from application to the movable member.